The invention of rechargeable lithium-ion (Li-ion) battery technology has set the standard in energy storage over the last several decades for powering portable phones, computers, and electric vehicles. While the demand for devices that provide faster data communication, increased computational power, brighter and higher resolution displays, and batteries with longer ranges, better performances, shorter charging times, at reduced weight and lower cost has increased over that time, the capability and development of lithium-ion batteries has not kept pace with this increase in demand.
As limitations of current Li-ion battery technology becomes more apparent, the need for alternative rechargeable battery technologies becomes more critical. One example of an attractive alternative to the current Li-ion battery technology is lithium-sulfur (Li—S) battery technology because of its potential for higher energy capacity and cost reduction from the use of sulfur. Most Li-ion batteries have energy capacity in the range of 150 to 250 Wh/kg, while Li—S batteries may offer energy capacity of 400+ Wh/kg. Therefore, Li—S batteries can have higher cell-level (and pack-level) capacity than current Li-ion batteries.
However, there is currently a lack of Li—S batteries that are commercially available due to many well-known technical challenges. One of the primary shortfalls of most Li—S cells is unwanted reactions with the electrolytes as dissolving intermediate polysulfides into electrolytes cause irreversible loss of active sulfur.
Another issue is the widespread use of sulfur-based cathode material that necessitates the use of lithium metal anode as the source for lithium for Li—S batteries. Lithium metal anode can be prone to dendrite growth that can cause thermal runaway due to internal short circuit of the battery. Further, using lithium anode, and in particular to Li—S batteries, can lead to undesirable side reactions as the polysulfide diffuses back and forth between the electrodes in a phenomenon known as the shuttle mechanism, which reduces the charge-discharge efficiency and cycle stability due to lithium corrosion and sulfur oxidation. Moreover, using lithium metal is not cost-effective, since commercial lithium anodes (typically Li thin foils) require sophisticated processes (purification, extrusion, passivation, etc.) because lithium is very active towards moisture and air (oxygen and nitrogen).
The present disclosure provides a solution to these problems by using a continuous and scalable aerosol spray pyrolysis (ASP) process to form lithium-sulfide-carbon composites, which can be a superior cathode material as compared to sulfur because the resulting structure of the material mitigates capacity fading due to the loss of active sulfur material. Further, when using lithium-sulfide as the cathode material, non-lithium high-capacity anode materials such as tin based materials and silicon based materials can be used in the lithium sulfur cell. Therefore, using the lithium-sulfide cathode material as described herein can also minimize or prevent the aforementioned disadvantages associated with the use of lithium metal anode.
Other possible approaches for synthesizing lithium sulfide may not be as scalable or provide the rationally designed structure of the material for the desired functionality. For example, lithium sulfide has been synthesized by ball-milling lithium sulfide and carbon as well as lithiation of conventional sulfur cathode materials. However, the lithium-sulfide cathode material of the present disclosure can provide a superior material for use in a battery (e.g., Li-ion, Li—S, etc.) as compared to the previous approaches. For example, since the ASP process allows the lithium sulfide to be more uniformly dispersed within the carbon matrix, the kinetics of charge transfer process can be improved to result in improved rate capability (the capacity to be discharged and charged at a faster rate). The uniform lithium sulfide dispersion in the carbon matrix can also effectively sequestrate the dissolution of lithium polysulfides thus alleviating the shuttle mechanism.
To better illustrate the encapsulated method and systems disclosed herein, a non-limiting list of examples is provided here:
Example 1 can include subject matter (such as a method) for forming a battery electrode. The method can include forming a precursor solution including a lithium sulfide precursor and a carbon precursor; converting the precursor solution into an aerosol; removing water from the aerosol to form precursor particles; reacting the precursor particles at a first reaction temperature to form lithium carbonate; and reacting the lithium carbonate with hydrogen sulfide to form a lithium-sulfide-carbon composite.
In Example 2, the subject matter of Example 1 can optionally be configured to include shaping an amount of the lithium-sulfide-carbon composite into an electrode.
In Example 3, the subject matter of any one or any combination of Examples 1 or 2 can optionally be configured to include where the lithium sulfide precursor is selected from lithium nitrate, lithium acetate, and lithium carbonate.
In Example 4, the subject matter of any one or any combination of Examples 1 through 3 can optionally be configured where the carbon precursor is selected from sucrose, glucose, and polyvinylpyrrolidone.
In Example 5, the subject matter of any one or any combination of Examples 1 through 4 can optionally be configured where the lithium sulfide precursor is lithium nitrate and the carbon precursor is sucrose.
In Example 6, the subject matter of any one or any combination of Examples 1 through 5 can optionally be configured where the lithium sulfide precursor is lithium acetate and the carbon precursor is sucrose.
In Example 7, the subject matter of any one or any combination of Examples 1 through 6 can optionally be configured where the lithium sulfide precursor is lithium acetate and the carbon precursor is sucrose.
In Example 8, the subject matter of any one or any combination of Examples 1 through 7 can optionally be configured where the lithium-sulfide-carbon composite includes about 50 volume percent to about 65 volume percent of lithium sulfide.
In Example 9, the subject matter of any one or any combination of Examples 1 through 8 can optionally be configured where the precursor particles have a water content of less than 20 percent.
In Example 10, the subject matter of any one or any combination of Examples 1 through 9 can optionally be configured where reacting the lithium carbonate with hydrogen sulfide includes reacting the lithium carbonate with hydrogen sulfide at a second temperature in a gaseous environment including an inert gas an hydrogen sulfide, wherein the second temperature less than the first temperature.
In Example 11, the subject matter of any one or any combination of Examples 1 through 10 can optionally be configured to include forming the gaseous environment.
In Example 12, the subject matter of any one or any combination of Examples 1 through 11 can optionally be configured where forming the gaseous environment including flowing argon and hydrogen over elemental sulfur.
Example 13, can include subject matter (such as a method) for forming a battery. The method can include obtaining or providing a first electrode, including: a lithium-sulfide-carbon composite formed by an aerosol spray pyrolysis process, wherein a plurality of lithium-sulfide particles are at least 70 weight percent of the electrode; obtaining or providing a second non-lithium containing electrode; and contacting an electrolyte with both the first electrode and the second non-lithium containing electrode.
In Example 14, the subject matter of any one or any combination of Examples 1 through 13 can optionally be configured to include forming the first electrode, including: forming a precursor solution including a lithium sulfide precursor and a carbon precursor; converting the precursor solution into an aerosol; removing water from the aerosol to form precursor particles; reacting the precursor particles at a first reaction temperature to form lithium carbonate; and reacting the lithium carbonate with hydrogen sulfide to form a lithium-sulfide-carbon composite.
In Example 15, the subject matter of any one or any combination of Examples 1 through 14 can optionally be configured where the lithium sulfide precursor is selected from lithium nitrate, lithium acetate, and lithium carbonate and the carbon precursor is selected from sucrose, glucose, and polyvinylpyrrolidone.
In Example 16, the subject matter of any one or any combination of Examples 1 through 15 can optionally be configured where the second electrode includes at least one of tin and silicone.
In Example 17, the subject matter of any one or any combination of Examples 1 through 16 can optionally be configured where the battery is a CR2032 form factor.
Example 18 can include an electrode including a carbon matrix; and a plurality of lithium-sulfide particles uniformly distributed into the carbon matrix, wherein the plurality of lithium-sulfide particles are about 70 weight percent of the electrode.
In Example 19, the subject matter of any one or any combination of Examples 1 through 18 can optionally be configured where the plurality of lithium particles are uniformly distributed into the carbon matrix via an aerosol spray pyrolysis process such that per one gram of carbon includes lithium-sulfide particles within the range of about 1 gram to about 2.5 grams.
Example 20 can include a battery. The battery includes a first electrode, including a plurality of lithium-sulfide particles coated with a carbon shell, a second electrode, and an electrolyte in contact with both the first electrode and the second electrode.
Example 21 can include the battery of example 20, wherein the plurality of lithium-sulfide particles coated with a carbon shell include a plurality of lithium-sulfide particles coated with an amorphous carbon shell.
Example 22 can include the battery of any one of examples 20-21, wherein the plurality of lithium-sulfide particles are about 70 weight percent of the electrode.
Example 23 can include the battery of any one of examples 20-22, wherein the plurality of lithium particles are uniformly distributed via an aerosol spray pyrolysis process such that per one gram of carbon includes lithium-sulfide particles within the range of about 1 gram to about 2.5 grams.